migrated SEPADirectDebitClientUnitTest and MockkSEPADirectDebitApiBui… (#1370)

* migrated SEPADirectDebitClientUnitTest and MockkSEPADirectDebitApiBuilder to kotlin

* PR review changes

* PR review changes

* Remove MockSEPADirectDebitApiBuilder.java and clean up SEPADirectDebitClientUnitTest

---------

Co-authored-by: Timothy Chow <tichow@paypal.com>

Author: sailaya99

SEPADirectDebit/src/test/java/com/braintreepayments/api/sepadirectdebit/MockSEPADirectDebitApiBuilder.java

@@ -0,0 +1,59 @@
+package com.braintreepayments.api.sepadirectdebit
+
+import io.mockk.every
+import io.mockk.mockk
+
+class MockkSEPADirectDebitApiBuilder {
+    private var createMandateError: Exception? = null
+    private var createMandateResultSuccess: CreateMandateResult? = null
+    private var tokenizeError: Exception? = null
+    private var tokenizeSuccess: SEPADirectDebitNonce? = null
+
+    fun createMandateResultSuccess(createMandateResultSuccess: CreateMandateResult?): MockkSEPADirectDebitApiBuilder {
+        this.createMandateResultSuccess = createMandateResultSuccess
+        return this
+    }
+
+    fun createMandateError(createMandateError: Exception?): MockkSEPADirectDebitApiBuilder {
+        this.createMandateError = createMandateError
+        return this
+    }
+
+    fun tokenizeSuccess(tokenizeSuccess: SEPADirectDebitNonce?): MockkSEPADirectDebitApiBuilder {
+        this.tokenizeSuccess = tokenizeSuccess
+        return this
+    }
+
+    fun tokenizeError(tokenizeError: Exception?): MockkSEPADirectDebitApiBuilder {
+        this.tokenizeError = tokenizeError
+        return this
+    }
+
+    internal fun build(): SEPADirectDebitApi {
+        val api = mockk<SEPADirectDebitApi>(relaxed = true)
+
+        every {
+            api.createMandate(any(), any(), any())
+        } answers {
+            val callback = arg<CreateMandateCallback>(2)
+            if (createMandateResultSuccess != null) {
+                callback.onResult(createMandateResultSuccess, null)
+            } else if (createMandateError != null) {
+                callback.onResult(null, createMandateError)
+            }
+        }
+
+        every {
+            api.tokenize(any(), any(), any(), any(), any())
+        } answers {
+            val callback = arg<SEPADirectDebitInternalTokenizeCallback>(4)
+            if (tokenizeSuccess != null) {
+                callback.onResult(tokenizeSuccess, null)
+            } else if (tokenizeError != null) {
+                callback.onResult(null, tokenizeError)
+            }
+        }
+
+        return api
+    }
+}